This U.S. patent application claims the priority of PCT International Application No. PCT/JP99/02946, filed on May 14, 1999, which was based on the priority of Japanese Patent Application No. 10-132090, filed on May 14, 1998.
This invention relates to an overhead traveling crane system capable of accurately controlling the position of a lifting device horizontally, the lifting device being suspended from the overhead traveling crane system and elevated thereby.
First, a description will be given of an outline of an electrolysis refinery facility (see FIG. 6). An electrolytic bath 30 is formed as a rectangular parallelepiped tank which is open upwardly and has a common conductor (bus bar) 32 set up on an upper surface of a side wall 30c of the electrolytic bath 30. As is most clearly shown in FIG. 5, a plurality of electrolytic baths 30 are arranged side by side longitudinally and laterally, and they come to several hundreds of tanks in total. In an electrolyte solution of each electrolytic bath 30, a plurality of cathode plates K (in case of Cu, normally between 20 and 50 sheets) and a plurality of anode plates A with lugs immersed alternately in parallel. Each of the cathode plates K is suspended from a cathode support bar (cross bar) 34. Both ends of the cross bar 34 as well as the lugs of the anode plates A are supported on an upper surface of one of left and right electrolytic bath side walls 30c and a common conductor provided to the other side wall 30c, respectively. In the electric current supply of a system as shown in FIG. 5, four electrolytic baths 30 are arranged in two rows longitudinally and two rows laterally to make one set, and are wired so that electric current flows from the anode plates A to the cathode plates K. Because an electrolysis refinery power source needs low voltage and a large amount of current and has, at the same time, a wide range of voltage adjustment depending on a condition of an electrolysis operation, a semiconductor rectifier of a thyristor system or a diode system is employed.
As primary factors that hamper normal operation of the electrolysis refinery, there are growths of branch shaped crystals or lumps on the cathode side, curvature of the cathode, and bridging of large anode fragments. For example, if a lump grows locally on the cathode side and hypertrophies, anode plate A and cathode plate K will short-circuit, so that the electrolysis current becomes concentrated on the short-circuited area, and the electrolysis refinery is hampered.
Tank inspection work to discover these errors is done by workmen walking on the electrolytic baths everyday. But this demands a great deal of labor because enormous parts must be inspected and workmen walking on the electrolytic baths may cause the position of an electrode plate to shift.
Accordingly, by utilizing the fact that the gain and loss of electric current and variation in magnetic flux have a certain relationship, the system is designed to measure the magnetic-flux density of the cathode plates K and/or anode plates A with a magnetic sensor and detect change of the electric current and to thus detect any error on the electrode plate. Furthermore, to make the inspection work automatic for measurement of the magnetic-flux density, the system is designed to utilize an overhead traveling crane system for salvaging electrode plates, suspending the lifting device from it, mounting a plurality of magnetic sensors on this lifting device, and placing each of the magnetic sensors adjacent to the cathode plates K and/or anode plates A supported by common conductors.
To measure the magnetic-flux density of each of the electrode plates, it is required that the overhead traveling crane system accurately positions the magnetic sensors close to the given places of the cathode plates K and anode plates A.
However, with the general-purpose model of the overhead traveling crane system, in addition to possible error like a rail construction error or a detector error, since there is only a little space between the system and each of the electrode plates (approximately 10 cm), it is usually difficult to operate the overhead traveling crane system to accurately position the magnetic sensors suspended from the lifting device close to the cathode plates K and/or anode plates A.
To minimize the error, it is conceivable to carry out the construction of the rail more minutely and suppress the play in oblique and lateral wheel movement to the utmost. However, in practice, it is extremely difficult to do so in a facility with the rail being several hundred meters long.
Moreover, if the elevation of the lifting device is based on the height measured in only one spot, the magnetic sensors might be displaced from their given positions close to the cathode plates K and/or the anode plates A by the inclination of the lifting device, and might not be able to measure the magnetic-flux.
Therefore, this invention has an object to provide a stopping device for stopping movement of a lifting device vertically in an overhead traveling crane system with an increased accuracy even when a general-purpose overhead traveling crane is used.
To solve the above-mentioned problem, the invention provides a stopping device for a lifting device of an overhead traveling crane system in which a moving device is arranged so as to be movable in a horizontal direction on a track laid on an upper space, and the lifting device is suspended from the moving device through a wire so as to ascend and descend, and wherein the stopping device descends and stops the lifting device to a given height with respect to a reference position defined on the ground. At least two locking members are attached to the lifting device so as to slide with it in up and down directions. A stopper is attached to an upper end of each of the locking members in order to prevent the locking members from falling off the lifting device. Contacting means are fixed to a lower end of each of the locking members in order to cause the locking members to stop descending by coming into contact with the reference position. Sensing devices are attached to given positions on the lifting device, and sensor elements to be sensed by the sensing devices are attached to the locking members. The locking members are caused to stop descending when the contacting means makes a contact with the reference position. The lifting device continues to descend until the sensing devices attached to the lifting device sense the sensor elements attached to the locking members, and then the lifting device is caused to stop descending.
To solve the above-mentioned problems, the present invention provides the stopping device for stopping the lifting device in the height direction of the overhead traveling crane system. The sensing devices on the lifting device include three sensing devices arranged in a vertical direction. The locking members are caused to stop descending when the contacting means makes contact with the reference position. A lower one of the three sensing devices senses a corresponding one of the sensor elements, so that the lifting device is decelerated. The lifting device is caused to stop descending when a middle one of the three sensing devices senses the corresponding one of the sensor elements. The upper one of the three sensing devices causes an emergency stop of the lifting device when sensing the corresponding one of the sensor elements.
The present invention also provides the stopping device for stopping the lifting device in the height direction [in] of the overhead traveling crane system wherein the contacting means includes disks which have a size that can contact a plurality of cathode supporting rods and are supported so as to rotate in a circumference direction thereof, the disks being supported by the lifting device so as to slide vertically on a ball bushing.
The present invention further provides the stopping device for stopping the lifting device in the height direction of the overhead traveling crane system wherein one or more magnetic sensors are suspended from and supported by the lifting device.
Each of the magnetic sensors is fixed to a tip of a Teflon pole, so that the magnetic sensors can be prevented from being damaged due to bending of the Teflon pole caused when the magnetic sensors strike the cathode supporting rods. The attachment positions of the magnetic sensors can be adjusted.